HY lecture notes:
This lecture is exceedingly HY for both pediatrics and family medicine shelves. This lecture is therefore a mandatory crosspost (Pediatrics #4).
You need to be aware of the CENTOR criteria, which is used to differentiate a viral from bacterial upper respiratory tract infection (URTI).
If 0 or 1 point, the URTI is unlikely to be bacterial (i.e., it’s likely to be viral). If 2-4 points, chance is much greater that URTI is bacterial.
CENTOR:
- Absence of cough (i.e., no cough = 1 point; if patient has cough = 0 points).
- Fever.
- Tonsillar exudates.
- Lymphadenopathy (cervical, submandibular, etc.).
There is a version of the criteria that includes age, but on the USMLE it can cause you to get questions wrong. So just use the simplified above four points.
If 0-1 point, answer = “supportive care”; or “no treatment necessary”; or “warm saline gargle” (same as supportive care).
If 0-2 points, next best step = “rapid Strep test.” If rapid Strep test is negative, answer = throat culture, NOT sputum culture.
While waiting on the throat culture results, we send the patient home with amoxicillin or penicillin for presumptive Strep pharyngitis.
If child is, e.g., 12 years old, and develops a rash with the beta-lactam, answer = beta-lactam allergy.
If the vignette is of a 16-17 year-old who has been going on dates recently (there will be no confusion; the USMLE will make it clear), the answer = EBV mononucleosis; therefore do a heterophile antibody test (Monospot test).
EBV is the odd virus out that usually presents with all four (+) CENTOR criteria.
This is why it’s frequently misdiagnosed as Strep pharyngitis. It is HY to know that beta-lactams given to patients with EBV may cause rash via a hypersensitivity response to the Abx in the setting of antibody production to the virus. EBV, in a patient who does not receive Abx, can cause a mild maculopapular rash. But the rash with beta-lactam + EBV causes a more intense pruritic response generally 7-10 days following Abx administration on the extensor surfaces + pressure points.
